Level of Service (LOS)
Approach
Level of service (LOS) designations are qualitative measures of
congestion that describe operational conditions within a traffic stream
and take into consideration such factors as volume, speed, travel time,
and delay. LOS is represented by letter grades, A through F. LOS A through
C imply traffic flows with minimal delay, while LOS D and E imply
conditions that approach capacity, and LOS F implies unstable flow with
potential for substantial delays (Transportation Research Board 2000).
Characteristics of the six LOS designations for roadway segments and
intersections can be found in the Transportation section of the
Capital Facilities Plan.
In General
A Traffic flowing freely
B Generally unimpeded traffic flow
C Slower but stable flow with minor delays
D Reduced speeds and increased delays
E Slow speeds and significant delays
F Stop and go traffic, High level of delay
Roadway Segment LOS
Kitsap County uses traditional engineering methodology to
evaluate LOS of roadway segments, which are sections of
roadway located between major intersections. Roadway travel
volumes are compared to roadway capacity to develop a ratio
known as volume-to-capacity (V/C). The volume-to-capacity
ratios relate directly to measures of level of service.
This table shows the relationships between LOS, V/C ratios,
and peak-hour free flow speed on a roadway segment:
|
LOS |
Volume to Capacity Ratio Range |
Percent of Free Flow Speed (Peak Hour) |
|
A |
0.50 and below |
90% or greater |
|
B |
0.60 to 0.69 |
70% to 90% |
|
C |
.70 to .79 |
50% |
|
D |
.80 to .89 |
40% |
|
E |
.90 to .99 |
33% |
|
F |
1.00 and above |
25% or less |
Intersection LOS
Kitsap County currently has LOS standards adopted only at the
roadway segment level. However, in more urban parts of the
County, it has been recognized that roadway operations may be
controlled more by intersection operations than overall
roadway segment operations. In these areas, the County has
also been regularly measuring and analyzing intersection LOS.
Intersection LOS is determined by the average amount of delay
experienced by vehicles at the intersection.
This table summarizes the LOS criteria for signalized
intersections:
|
LOS |
Average Delay per Vehicle (seconds/vehicle) |
|
A |
≤ 10 |
|
B |
> 10 20 |
|
C |
> 20 35 |
|
D |
> 35 55 |
|
E |
> 55 80 |
|
F |
> 80 |
For stop-controlled intersections, LOS depends on the
amount of delay experienced by drivers on the stop-controlled
approaches. The LOS criteria for stop-controlled intersections
have different threshold values than the criteria for
signalized intersections, primarily because drivers expect
different levels of performance from distinct types of
transportation facilities. In general, stop-controlled
intersections are expected to carry lower volumes of traffic
than signalized intersections. Thus, for the same LOS, a lower
level of delay is acceptable at stop-controlled intersections
than it is for signalized intersections
This table summarizes the LOS thresholds for stop-controlled
intersections:
|
LOS |
Average Delay per Vehicle (seconds/vehicle) |
|
A |
≤ 10 |
|
B |
> 10 15 |
|
C |
> 15 25 |
|
D |
> 25 35 |
|
E |
> 35 50 |
|
F |
> 50 |
Tables listing existing and 2025 intersection LOS can be
found in
Volume II, section 3.2.6 of the County Comprehensive Plan FEIS
LOS Standards
LOS standards are used to evaluate the transportation impacts of long-term
growth and concurrency. Jurisdictions must adopt standards by which the
minimum acceptable roadway operating conditions are determined and
deficiencies may be identified. LOS standards for county
arterials and state highways, located within Kitsap County, involve three
different policy approaches established by Kitsap County, PSRC, and WSDOT.
While somewhat diverse in application, all the standards and methodologies
are consistent with the Highway Capacity Manual (Transportation Research
Board 2000) definitions and procedures.
County Roadways
Kitsap County's LOS policy generally recognizes that urban areas are
likely to have more congestion than rural areas. This reflects the
different characteristics of land use and transportation in these areas.
For purposes of defining LOS standards, urban areas are the geographic
areas located within a UGA boundary, and rural areas are the geographic
areas located outside of all UGA boundaries.
The LOS standards shown in the table below are based upon the location and
functional classification of the roadway facilities to which they apply.
Though the Countys goal is to have no LOS deficiencies, it is recognized
that not all roadways will meet the standards all the time given the
limits of county, state and federal funding and timing of project
implementation. Therefore, 15 % of the lane miles tested for concurrency
will be allowed to temporarily exceed LOS standards. This 15 % allowance
shall be applied at both the system wide and project site level.
|
Functional Classification |
Maximum V/C Ratio/LOS Standard |
|
Urban1 |
Rural2 |
|
Principal Arterial |
.89/D |
.79/C |
|
Minor Arterial |
.89/D |
.79/C |
|
Collector |
.89/D |
.79/C |
|
Minor Collector |
.89/D |
.79/C |
|
Residential/Local |
.79/C |
.79/C |
Tables listing existing and 2025 roadway LOS can be
found in
Appendix K, Volume II of the County Comprehensive Plan DEIS, along
with a
map of projected deficient roadways.
| Roadway Deficiencies |
| |
North |
Central |
South |
County-Wide |
|
2006 |
7.5 % |
2.2 % |
3.4 % |
4.3 % |
|
2025 |
15.2 % |
7.0 % |
24.8 % |
16.4 % |
Kitsap County Public Works
Kitsap 1
(360) 337-5777 or (800) 825-4940
Kitsap1@co.kitsap.wa.us
|
